As you leave the theater after watching “77%” by Rinne Groff, directed by Claudia Weill, the third offering of the Vineyard Playhouse summer season, you’ll have that itchy feeling you’ve experienced before when you’ve sipped wine and shared a meal with married friends whose affinity is foundering. As you leave, you might ask your companion, “How much time do you give them? Six months?”

Eric (Chris Henry Coffey) and Melissa (Ali Marsh), somewhere in their, oh, mid-40s? are tightly packed with tension — tension about life, about a stable of modern-day quandaries that most Gen-Xers and millennials have collected along with their sets of IKEA furniture, and tension triggered by each other, because they’ve fallen into their rather conventional mess and can’t see their way out of it, except with one supreme stalling device: They want a baby. They’ve got two little kids who are now safely potty-trained and therefore sailing off into the real world, so a new baby is needed fast. A baby is, if nothing else, a bomb going off in the house, so that nothing else concerns Mommy and Daddy except dealing with the debris and the fallout.

There’s a twist, a rather common one. Melissa is past her fertility prime, so they’re doing the whole hospital rumba with injections of hormones, metal trays of extracted ova, and the husband in a private cell with a stack of sexy magazines (not that we see this part, of course).

There’s another twist, a major aspect of postmodern relationships: Melissa, a savvy businesswoman, is the bigger breadwinner; in fact, her bread is a virtual bakery of loaves, whereas Eric, who watches the kids, works with half a loaf: He’s an underpaid illustrator of a children’s book series about caterpillars. “Not butterflies,” he adds bitterly.

It’s Eric, caught in the existential netherworld that once belonged almost exclusively to women, of raising kids and dallying with this and that creatively, who all the while dreams of a bigger picture that may never unfold — why would it?

Meanwhile, another couple undergoes a different half-idyll, half-agony: Melissa’s mother, Frankie (Karen MacDonald) is bunked with Melissa, Eric, and the kids, while Melissa’s dad, Nelson, is literally out to sea: He’s either fully incommunicado or “pixillating” on his iPhone; he’s taken the beloved family sloop on a “farewell voyage.” Does this mean he’ll drown, wash up in Tahiti, or he’ll finally dry-dock the sloop and hang up his yellow slicker?

Melissa tells Eric her folks are “mutually antagonistic.” So what does that make Melissa and Eric? Chopped liver? Whatever, Frankie seems unconcerned; she’s much more easygoing than her daughter, but maybe that’s a consolation of age. She’s freed up from a big career and the tribulations of a harvested embryo implanted in her uterus.

The crowning scene takes place when Melissa is incommunicado herself on yet another business trip, and Eric finds his mother-in-law drunk on cooking sherry. “It’s all you people have,” she complains, at which point he brings out the good stuff and they both get royally stewed.

Frankie identifies with Eric’s sense of professional shame from her own days of mommy freeze-frame: “How do we explain ourselves at parties?”

“I don’t know where my wife is,” he says plaintively.

She likens this to all the times Nelson disappears at sea and she’s met with the stark rejection of “radio silence.” Radio silence becomes the metaphor for that virus that slowly steals its way into twined lives, and sucks the juice out of them, just as Eric’s caterpillars sponge off the twigs they climb.

Meanwhile, the playhouse with its gorgeous new stage has launched a state-of-the-art FX campaign, never more vivid than in this play. Panels slide back and forth, with projections of highway signs, light signals as psychedelic fireworks; caterpillars up close and personal, shockingly cute, green with little brown pads for feet as they plod their way up branches. Big kudos go to scenic designer Mac Young, lighting designer Jeffrey E. Salzberg, light board operator Brendan Rome, sound designer David Remedios, technical director Boaz Kirschenbaum, and projection designer Jeff Larson: These artists tip the audience over into a zone where we’re immersed in the intimate actions of a play at the same time that we’re watching a movie.

Little, therefore, is needed in the way of actual stage paraphernalia; a bench-desk-table is used for the front seat of the new minivan Melissa happens to hate, a bathroom, a kitchen counter, an examining room, a living room, and a hospital waiting room, back and forth, with the minivan and roving highway lights somehow anchoring the life of this unmoored couple, with their iPhones, of course, an unstoppable backup: this brave new world’s new larynx.

Ms. Marsh portrays the soul — or perhaps it’s more poignant to say the persona with the soul extruded — of an overworked woman whose ovaries are being surgically poked in her limited downtime. Mr. Coffey may remind you of Jack Nicholson in “The Shining,” and this is a positive thing; his good nature is a sponge — a caterpillar — for his wife’s relentless edge. And the character of Ms. MacDonald explains why older women are needed in the world, their hormones still churning out maternal love, softened over time, unhampered by actual children — grandkids are easier, we know that — with their husbands at sea under the restraint of “radio silence,” so they can mop up the silly, frenzied, culturally engendered emotions of their own grown offspring.

This is not a spoiler, only an inducement to come see this play; as grim as it might sound, it’s funny and witty throughout, and even manages to end on a happy note, although this perfect moment is doomed to be fleeting, what with crazy culture in which we try to survive.

And why “77%” as a title? Well, at a moment of grand effusion, Eric proposes to cover 100 percent of his wife’s body with 100 percent of his own. Melissa deems this an impossible feat, but they try out different groping strategies to find the highest skin-to-skin ratio.

“77%,” playing at the Martha’s Vineyard Playhouse, nightly Wednesday through Saturday, until August 15. For additional information visit vineyardplayhouse.org.